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MacOS may lose data on APFS-formatted disk images

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Re: MacOS may lose data on APFS-formatted disk images

#51

Post by blattimwind »

eropple wrote: post #48
derefr wrote: post #39

I tend to create sparsebundles to clone my git repos within, to get around the overhead of having huge numbers of inodes on a volume. (Copying, deleting, unpacking archives, Spotlight indexing—all are way slower when you have the worktrees and .git directories from a thousand large repos splayed out across your disk.) So I was a little worried here. Thankfully, I had manually been setting my sparsebundles back to HFS…

This is a neat idea, I've never thought about doing that. You should write a blog post about it.

TBH an I/O system where having a file system inside a loopback device on another file system is faster than using said file system directly in the first place sounds kinda broken-ish/poorly scaling to me.

Re: MacOS may lose data on APFS-formatted disk images

#52

Post by bhj »

voldemort1968 wrote: post #35
wiradikusuma wrote: post #20

I upgraded my hackintosh to High Sierra with APFS. The next day, I accidentally switched off the machine while it was in the _process_ of shutting down (the screen had gone blank, but casing still emitting lights). Next time I turned it on, I couldn't get past login screen (giving me forever beach ball). I put the ssd inside my old MBP as slave to recover data. The ssd was corrupted, most data gone, as in shown in Fi…

...So not an actual Apple Product.

My (limited) understanding of APFS is that it forgoes some integrity checks on the assumption that they have already been done by lower-level hardware. This is of course a debatable design decision, but it may indeed be unwise to use APFS on non-Apple hardware.

Re: MacOS may lose data on APFS-formatted disk images

#53

Post by tankenmate »

agildehaus wrote: post #32

Can you even test a filesystem properly internally? Seems to me we're all involved in a massive public beta.

Apple authored a tool called fsx (file system exerciser), but I doubt it checks for corner cases for loopback mounts. Maybe they should add such tests.

Re: MacOS may lose data on APFS-formatted disk images

#54

Post by alwillis »

kbumsik wrote: post #40

Two bugs are described in this article: 1. An APFS volume's free space doesn't reflect a smaller amount of free space on the underlying disk 2. The diskimages-helper application doesn't report errors when write requests fail to grow the disk image These are not even complex problems of the new format. It is just Apple forgot to have basic checks. It is like the root access with an empty password incident happened 2 m…

This is by far the best explanation of what’s happening at Apple and why we’re noticing these bugs and problems: https://www.imore.com/understanding-apple-scale

Re: MacOS may lose data on APFS-formatted disk images

#55

Post by freehunter »

StillBored wrote: post #46
toasterlovin wrote: post #16

Earlier quoted context omitted.

As a counterpoint, APFS was deployed to almost a billion devices over the span of several months when it was release and, IIRC, this is the first major issue.

How do you know that? Filesystem corruption is frequently silent, and every-time it happens customers don't get on the phone and send the disks to apple so that they can root cause the problem. Its quite possible this bug has happened an untold number of times before it happened to someone who went through the effort to reproduce and isolate it.

>How do you know that?

Can you point to any other APFS issues that were reported before this one?

Re: MacOS may lose data on APFS-formatted disk images

#57

Post by eropple »

blattimwind wrote: post #51
eropple wrote: post #48

Earlier quoted context omitted.

This is a neat idea, I've never thought about doing that. You should write a blog post about it.

TBH an I/O system where having a file system inside a loopback device on another file system is faster than using said file system directly in the first place sounds kinda broken-ish/poorly scaling to me.

Having Spotlight ignore .git directories and the like is probably wise, I would agree with that. But it's text, even if it's basically garbage text (from a user perspective). So I can understand how a sparsebundle is a decent end-around.

The Finder in general ends up basically being useless for me for similar reasons; I have dozens of random dependency files I don't even recognize pop up in "All My Files".

Re: MacOS may lose data on APFS-formatted disk images

#58

Post by exikyut »

banned1 wrote: post #41
threeseed wrote: post #29

Earlier quoted context omitted.

Quite a few non-Apple network devices support Time Machine. I back up every day to my Synology NAS for example.

Unrelated (sorry for being opportunistic): How do you like your Synology NAS? I’m considering it.

Not the person you replied to, but I want to make a case for ZFS on a generic small motherboard. You wind up with Linux or FreeBSD so it's a general-purpose server, unless you want to use something like FreeNAS. And with ZFS, you get snapshotting, RAIDz, checksumming, etc, as opposed to "oh it has RAID 5 woohoo".

RAID (including the software RAID in Linux) doesn't actually do checksumming for file verification. AFAIK, ZFS is the only open system to do so.

Re: MacOS may lose data on APFS-formatted disk images

#59

Post by freehunter »

sbuk wrote: post #36
FreakyT wrote: post #21

Earlier quoted context omitted.

Honestly, it's the first Mac OS release I'd actively recommend avoiding upgrading to. It offers essentially no benefits over the prior release, and a whole lot of downsides. (Security issues notwithstanding, High Sierra also drops compatibility for a lot of older software.)

As did other versions of OSX[0]. This whole meme should get a law like Betteridge’s. Complaints about the current release of macOS are as old as the hills[1] and have become entirely vacuous. That’s not to say the complaints aren’t necessarily without merit; just that there is too much hyperbole around them. [0] https://forums.macrumors.com/threads/apps-that-wont-work-on-... [1] https://youtu.be/GWxC8ezE4Dk

As well as every version of every OS ever. Windows 98 was the best, Windows XP sucked with it's Fisher Price UI. Then Vista/7 came around and the outcry of "if you want the latest DirectX, you have to upgrade". And then Windows XP was discontinued to much wailing and gnashing of teeth, because XP was the best. Then 8/10 came out and everything was terrible and we're just going to stick to Windows 7 because it's the best.

To many techies, version n-1 is the best thing ever created, until version n+1 comes out and the "best ever" shifts up one revision.

Re: MacOS may lose data on APFS-formatted disk images

#60

Post by dreamcompiler »

huslage wrote: post #50
kbumsik wrote: post #40

Two bugs are described in this article: 1. An APFS volume's free space doesn't reflect a smaller amount of free space on the underlying disk 2. The diskimages-helper application doesn't report errors when write requests fail to grow the disk image These are not even complex problems of the new format. It is just Apple forgot to have basic checks. It is like the root access with an empty password incident happened 2 m…

(1) is incorrect. Sparsebundles are capable of over-provisioning the storage below them _by design_. They always have been. They are, I believe, APFS snapshots essentially now. This behavior is consistent with most other filesystems with similar constructs. (2) is the real issue here.

> Sparsebundles are capable of over-provisioning the storage below them _by design_.

According to TFA, HFS+ sparsebundles reflect the limitations of their underlying volume, while APFS sparsebundles do not. Seems clear to me that this is a bug.

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